In the production of glass fiber filaments, it is well known to flow molten glass from a suitable source into a bushing assembly. A bushing assembly is generally an elongated channel having side and end walls and a generally planar bottom which includes a large number of nozzles or tips through which the molten glass passes. In the zone immediately below these tips, the molten glass is formed into filaments, which normally then have a sizing applied to them and are gathered into a strand, and wound onto a package.
The environment in the zone immediately below the tip plate is crucial in the formation of the filaments because it is this area that the molten glass cools and changes into the filaments. For example, it will be appreciated that temperature fluctuations in this zone will result in diameter variations in the strands. Filaments subjected to more rapid cooling in one portion of the zone than in another portion of the zone will have larger diameters and may not withstand the gathering and winding forces applied to them causing breakage of the filament. Conversely, filaments which are undercooled may break due to instability.
The tip plate and molten glass is cooled by a finshield assembly including cantilevered cooling fins. The finshield assembly is located beneath the bushing tip plate and frequently must be taken down from its use location for cleaning, repair, or for adjustment of the fin geometry caused by tip plate deformation or warping. The means for securing the finshield assembly and cooling fins to the bushing must be secure yet quickly releasable. A generally permanent nut and bolt connection is usually not suitable for this application since such a connection would not be quickly and readily undone. The high operating temperature in the glass fiber forming area in combination with the glass volatiles that are released during glass fiber formation, together with the presence of cooling water sprays and the like combine to render a conventional nut and bolt attachment of the finshield assembly to the bushing assembly unacceptable.
In addition, to the requirement for precise control of the temperature environment in the formation of glass filaments and easy attachment of the finshield assembly, it will be further appreciated that stray air currents can also carry unwanted materials into the zone thereby breaking the filaments and decreasing production efficiency.
For a more detailed description of the operating environment and construction of a glass fiber forming apparatus, reference is made to U.S. Pat. Nos. 4,325,722; 4,391,618 and 4,566,891, incorporated herein by reference.
In view of the foregoing, it will be appreciated that there is a need for effective control of the environment in the zone directly beneath the tip plate. An object of the present invention is to provide an advanced fin positioner to operatively control the position of the finshield assembly. Another object of the present invention is to provide an advanced fin positioner that is compact in design. Yet another object of the present invention is to provide an advanced fin positioner of a modular design for easy rebuild or repair. Still another object of the present invention is to provide an advanced fin positioner that is capable of operating at temperatures of 600 degrees fahrenheit without warpage. Another object of the present invention is to provide an advanced fin positioner that is simple and economical to manufacture.